Duplex horn for sound reproducers



May 27, 1930. g 'HFIE D 1,760,284

.DUPLEX HORN FOR SOUND REPRODUCERS Original Filed Feb. 27,. 1922 Patented May 27, 1930 U ED STATES PATEN'If. OFFICE enovnn G. REHFIELID, OF CHICAGO, ILLI1\I 0IS,'.ASSIGNOR, BY ima ASSIGNMENTS,

T RADIO CORPORATION or AMERICA, on NEW YORK, N. Y., A CORPORATION 01 DELAWARE DUPLEX HORN FOR SOUND REPRODTUCERS Application filed February 27, 1922, Serial No. 539,366. Renewed February 21, 1925..

My invention relates to sound reproducers adapted for reproducing sounds from two graph and those reproduced by a wirelessreceiving set. Where both phonograph rec-- ords and a wireless receiving set are available, the reproduction of sound from the two sourcesis not ordinarily desired at one and the same-time. Consequently, a single amplifying horn should be adequate for use with the sound reproducers associated with both ofthe said sources of sound. However, if reprod'ucers are attached to one and the same horn, the unused inlet connection affords a chamber which tends to reflect the tones from the reproducer which is in use and which undesirably modifies the sounds before they are emitted from the amplifying horn. In .0118 aspect, my invention aims to overcome this difficulty by providing an effective arrangement whereby either of two tone reproducers associated with a single amplifying horn can effectively be connected to the horn while operatively .disconnecting the other reproducei', and aims to effect this selective connection of the amplifying horn to either sound repro'ducer without any modification of the sound emission from the reproducer which is being used.

Furthermore, my invention aims to provide simple'means whereby this selective connecting of the amplifying born to one reproducer and the corresponding disconnection from the other reproducer can automatically be effected in response to the operation o f the apparatus associated with one reproducer. Where the record table ofthe phonograph is propelled by an electric motor, my

invention also aims to provide simple meansfor automatically causing the supplying of current to the motor to change the horn connection from the reproducer of the wireless receiving set to the tone arm of the phonograph. Furthermore, I'aim to provide sound passages connected with the inlet end of the amplifying horn and so formedas to present continuously flaring passages from either reproducer to the mouth of the horn,

thereby avoiding any distortion of the tonal effects.

More particularly, I aim to provide an amplifying arrangement suitable for use interchangeably with 'a radiophone and a phonograph, and aim to provide simple means whereby a single amplifying horn will normally be connected to the sound reproducer of the radiophone, whereby the connection .Wlll automatically be switched to. the tone arm of the phonograph when the motor of the phonograph is started, and whereby the connection will be switched back to the radiopone when the phonograph motor is stopped. Still further and also more detailed objects will appear from the following specifications and from the accompanying drawings, in which Fig. 1 is a fragmentary vertical section through the cablnet of an electrically driven phonograph equipped with my invention,

with the amplifying horn and the inlet connection s thereto shown in longitudinal section.

Fig. 2is a similar section through the portlon of the cabinet below the record turn 'table, showing the amplifying horn and the inlets thereto in elevation and showin one form of magnetic means for automatlcally shifting the horn inlet connection from the radiophone reproducerto the tone arm of the phonograph. v

Fig. 3 is a phantom view of the amplifying horn and of the inlet connections to the same, showing desirable cross sections for these parts and also showing the valve or flap which selectively controls the inlet c0nnectlons.

In the embodiment of the showing a phonograph cabinet 1 having mounted therein a phonograph including a record table-'2 adapted to be rotated by an electric motor 3. "The reproducer. 4 of the phonograph is connected by the usual tone arm 5 to a neck 6 leading first downwardly and then through a bend into the smaller or inlet end of an amplifying horn 7. Adjacent to the juncture of the neck 6 with'the inlet end of the horn and desirably arranged symmetrical to the said neck is an auxiliary drawings, I am arms of the Y at. the back of the interior ofinlet 8 leading to a radiophone reproducer 9 which is connectedby Wires 10 to a radiophone receiving system. The 'two' inlets 6 and 8 are desirably connected to the neck end of the amplifying form in substantially a Y formation and adjacent to the juncture of the the said connecting chambers I pivot a flap or Valve 11. This flap is desirably mounted on a rock-shaft 12 extending beyond the exterior of the tubular members forming the said inlet connections and is connected to suitable means for rocking the shaft so as to present the flap or valve in either of the'two operative positions in which it selectively connects one or the other of the inlets to the amplifying horn. For this purpose, I am here showing the rock shaft 12 as having fastened to it an arm 13 carrying thecurved core 1 1 of a solenoid whose winding 15 is connected inseries with one of the wires 16 through which current is supplied to the motor 3. Moreover, the solenoid core and the arm '13 are so disposed, as for example after the manner shown in Fig. 2, that gravity Will normally swing them in a clockwise direction, thereby swinging the flap 11 to the position shown in full lines in Fig. 1 or that in which this flap closes the connection from the tone arm of the phonograph to the aniplifyinghorn 7 and opens the corresponding con motion to the rad-iophone reproducer 9.

Consequently, the operator of such a duplex,

sound reproducing appliance can operate his radiophone" at any time and can have the resulting tones or other sounds amplified by the horn 7 "without paying any attention to the position of the flap. or valve 11 or to any other of the parts above described; Likewise, if he wishes to use the phonograph, he merely switches on the current for the operating motor in the usual manner, in doing Which he causes the current to energize the coil 15 so that the pull of this on the coil 14 will swing the rock-shaft to the position shown in dotted lines in Fig. 1. In other words, gravity normally maintains, the connection tothe wireless receiving set, starting the phonograph automatically shifts the connection to the latter, and gravity restores the connection to the radiophone whenever continuation of the outer surface of one of the inlet bends when in either of its two operative positions. In other words, I am able to maintain tonal passages which will gradually increase in, cross-section towards the mouth of the horn with substantial uni formity from each of the inlets, and my construction permits me to. dothis without introducing complications of any kind and without affording side passages which might tend to mufiie or distortthe'tones or other inlets respectively associated with the phonograph and with the wireless receiving set,'

means including a movable Valve for norcally shutting off the inlet connection to the phonograph, and automatic means for moving the valve to caus'e'the same to shut off the inlet connection associated with the wireless receiving set when the phonograph is in operation.

2. Asound reproducing apparatus comprising a wireless receiving set, a phonograph, an amplifying horn having a pair of inlets respectively associated with the phonograph and with the wireless receiving set, movable means normally actuated by gravity for shutting off theinlet connection to the phonograph, while leaving the wireless receiving set connected to the horn through the other inlet, and automatic means for annulling the said shut-0E of the phonograph and shutting off the inlet connection to the wireless receiving set when the phonograph is in use.

3. A sound reproducing apparatus comprising a wireless receiving set, a phonograph, an amplifying horn having a pair of inlets respectively associated with the phonograph and with the wireless receiving set, a control member arranged for shutting off either one or the other of the inlets, means for normally holding the control member in a position in which it shuts off the inlet from the phonograph, and control'means responsive to the operation of the phonograph for moving the control member to the position in which it shuts off the inlet connection to the Wireless receiving set and establishes the inlet connection to the phonograph.

4. A sound reproducing apparatus comprising a wireless receiving set, a phonograph, an amplifying horn having a pair of inlets respectively associated with the phonograph and with the wireless receiving set, a control member arranged for shutting off either one or the other of the inlets, an electf i motor for drivin 'the phonograph, mo vable means arrange for normally holding thec'ontrol member in a; position in which-it 'shuts off. the inlet c'oimection from the phonograph, controlmeans responsiveto the sup'pl y' of current to the motor for moving the control member to a position in which it receiving 'set.

5. Sound reproduoihg a ppai'atus per i claim 1,' incl'uding'a flick shaft, the control member being fast upon said rock shaft; the control means "includin nectiohs whereby the solenoid rocks the shaft.-

- {Signed at Chicago, Illinois, February 24th,

GROVER elREH i L shuts off the-inlet-conneotio to the wireless a solenoid having I 'lt's wlndmg'm serles W 1t the motor, and con- 

